WO2001082353A1

WO2001082353A1 - Device and method for polishing outer peripheral chamfered part of wafer

Info

Publication number: WO2001082353A1
Application number: PCT/JP2001/003307
Authority: WO
Inventors: Kazutoshi Mizushima; Atsushi Shiozawa; Naoyuki Takamatsu
Original assignee: Shin-Etsu Handotai Co., Ltd.
Priority date: 2000-04-24
Filing date: 2001-04-18
Publication date: 2001-11-01
Also published as: TW517325B

Abstract

A wafer outer peripheral chamfered part polishing device capable of polishing the outer peripheral chamfered part of a wafer by allowing a rotatably held wafer outer peripheral chamfered part to abut on a rotating cylindrical polishing drum (1) having an adhesive cloth (1a) stuck thereon and sliding the outer peripheral chamfered part relative to the polishing drum to uniform a polishing speed varying depending on polished portions so as to uniform a polishing amount, characterized in that an angle (υ) formed by the principal plane of the wafer and the rotating axis of the rotating cylindrical polishing drum is differentiated continuously or intermittently, and the wafer and cylindrical polishing drum are moved relatively to each other in such directions as to move toward and away from each other, following up to or in synchronous with a variation of the angle.

Description

Description: Polishing device and polishing method for the outer peripheral chamfer of the wafer

The present invention relates to a method and an apparatus for polishing an outer peripheral portion of a semiconductor wafer 18. Background art

The outline of the manufacturing process of a mirror surface of a silicon semiconductor or a compound semiconductor is as follows. First, a single crystal ingot manufactured by a process such as pulling is sliced in a disk shape to obtain a prototype of a mirror. Next, lapping is performed to obtain the flatness of the front surface and the parallelism of the front and back surfaces by shaving a considerably large uneven layer on the front surface generated by the slice. The wafer which has passed through these machining processes has a damaged layer, ie, a work-affected layer, on its surface, and is removed by chemical etching. Finally, polishing for mirror finishing of the surface is performed.

The semiconductor mirror surface wafer thus manufactured is put into the next device manufacturing process. The device manufacturing process further includes a substrate process, a wiring process, and a test process. In the substrate process, the substrate structure of the basic device is formed, and then, after the wiring process related to the formation of the wiring pattern and other structures, it is cut into device chips and passed to the assembly process.

As can be seen from the process from the above-mentioned single crystal ingot to the production of a semiconductor device, most of the processes are performed in the state of A.8. Also in the process, the substrate process and the wiring process are handled in an e-a state. In this area, operations using the outer periphery of the A8, such as automatic transport, are frequently repeated. For this reason, if the outer peripheral portion of the disc-shaped A-A8 is in a right angle state with the cut, chips and chips are likely to be generated, and the resulting particles will adhere to the main surface and reduce the production yield in the post-process Let it. Therefore, so-called chamfering is performed, in which the outer peripheral portion of the A8 is inclined or rounded at a certain angle. Also, if the outer surface has a rough surface, the chemicals used in the etching process etc. The cleaning of the quality is not completely carried out and remains, adversely affecting the subsequent steps. Furthermore, when the single crystal is subjected to epitaxy growth or the like on the main surface of the wafer and the degree of product processing as the wafer is increased, a plurality of so-called nodules may be present depending on the irregular and defective crystal arrangement state of the outer peripheral surface. This leads to disadvantages such as the formation of projections and crowns (continuous projection-like crystal growth) around the main surface. Therefore, in the processing of p.18, not only the processing of the main surface but also the processing of the outer periphery is important. At present, the outer periphery is polished to a mirror surface in addition to chamfering and prepared for chipping. In general, the surface should be highly conditioned.

That is, the outer peripheral portion of the wafer is subjected to a chamfer processing step, and then to a mirror polishing step of polishing the portion to a mirror surface. In the chamfer processing step, grinding is first performed in order to adjust the chamfered shape of the outer peripheral part to match the cross-sectional profile of the chamfer. In this process, deep streaks (scratches) are generated due to the effect of the abrasive grains falling off the grindstone and the change in the shape of the grindstone. Therefore, the chamfered portion must be etched or mirror-polished at least until the streak is removed.

In addition, for the processing of the outer periphery of the wafer, a tape with abrasive particles carried on the surface is used to reduce the processing load of mirror-beveling using a polishing cloth. However, processing distortion may be more likely to occur than processing using a polishing cloth, and in order to completely remove the distortion, it is necessary to carefully mirror-polish the surface using a polishing cloth.

The polishing apparatus used for this mirror-polishing is a cylindrical polishing drum 21 having a polishing cloth 21 a adhered to a cylindrical polishing drum peripheral surface as shown in FIG. A wafer holding device 20 that presses the outer chamfered portion against the cylindrical polishing drum 21 at a predetermined angle, a wafer W, and a polishing agent (not shown) for supplying an abrasive to a contact portion of the polishing cloth. Devices with nozzles are commonly used. In such a process of mirror polishing the wafer outer peripheral portion, it is naturally necessary to quantitatively grasp the processing capability and control the polishing state. Specifically, it is necessary to determine the appropriate processing time and polishing amount by grasping the unevenness of the roughness of the wafer outer peripheral portion and the polishing amount per unit time.

However, mirror polishing is performed with this conventional device, that is, with a fixed angle at all times. When the polishing method around the wafer was examined in detail, the polishing amount was partially different, and it was found that the polishing was not optimal.

That is, for example, as shown in FIG. 1, the wafer holding device 20 is fixed so that the wafer W and the polishing cloth 21a normally form an angle of about 45 degrees, and the wafer A and the polishing cloth 21a are fixed. Contact, as shown in the enlarged view of FIG.

It was confirmed that the polishing amount (polishing rate) was different at the positions of ② and ③.

Conventionally, the polishing amount has been evaluated based on the change in weight before and after processing, and only an average value of the wafer W can be obtained, and there is no means for measuring the thickness removed for each part.

The inventor of the present invention has previously disclosed, as Japanese Patent Application No. 11-37 1655, the processing speed and the processing speed of the workpiece to be processed in the step of processing the outer periphery of the wafer on the surface of the wafer as a substrate. The processing speed when the product is actually processed is defined as the processing speed of the material to be coated. A method for evaluating the processing capability of the wafer outer peripheral portion, which can be converted from the relative ratio using the processing speed of the evaluation device A8 of the present invention, was disclosed. It was made possible to measure the thickness that was scraped off at each site. According to the present invention, when the product A8 to be processed is a single crystal silicon A8, when a polysilicon layer is formed on the surface of the single crystal silicon layer 18 serving as a substrate, the single crystal silicon and the polysilicon are formed in the processing direction. A clear boundary line is created, and accurate machining can be evaluated based on this position.

According to this technique, when the surface of the single-crystal silicon wafer 8 is mirror-finished, in particular, when the polysilicon layer is coated on the wafer whose outer peripheral portion is mirror-polished, the boundary becomes clearer, so that a more accurate value is obtained. can get.

However, the above technique is merely an invention for evaluating the polishing ability, and does not suppress the variation in the polishing amount of the outer peripheral chamfer.

Then, the variation in the amount of polishing of the outer peripheral chamfer evaluated by the invention, that is, as shown in the enlarged view of FIG.

If the amount of polishing differs at the position of (3), (4) Depending on the roughness of the outer peripheral chamfer, polishing residue (a small amount of polishing leaving a rough surface) or conversely polishing residue Controls such as prolonging the machining time were necessary to prevent this from happening, which had a major effect on productivity. Disclosure of the invention

The present invention has been made in view of the above problems, and when polishing an outer peripheral chamfered portion, the polishing rate according to a processing portion is made uniform and the polishing amount is made uniform, that is, the in-plane distribution of the polishing rate and the polishing amount are reduced. An object of the present invention is to provide a polishing and polishing method and an apparatus for improving the dispersion.

In order to solve such a problem, the present invention provides a method for polishing a cylindrical polishing drum in which a polishing cloth is attached to a cylindrical peripheral surface and a wafer while rotating the wafer together and pressing the periphery of the wafer against the polishing cloth. In a method of polishing a wafer outer chamfer while rubbing a cloth against the wafer outer chamfer,

During polishing, the angle at which the wafer comes into contact with the polishing cloth is changed continuously or stepwise, and the outer peripheral chamfered part of the wafer is pressed against the polishing cloth following or synchronizing with the change in the angle. The present invention proposes an invention characterized in that the wafer A and the cylindrical polishing drum are relatively advanced and retracted in the direction of contact and separation so as to be in contact with each other, and the outer peripheral chamfered portion of the wafer is polished. As an apparatus for effectively implementing the invention, a cylindrical polishing drum having a polishing cloth adhered to a cylindrical peripheral surface and a wafer are rotated together and the outer peripheral portion of the wafer is pressed against the polishing cloth. Then, the polishing cloth is rubbed against the outer peripheral chamfered portion of the wafer, and a mechanism for polishing the outer peripheral chamfered portion is provided.

Reciprocating means for relatively reciprocating the wafer outer peripheral chamfered portion and the cylindrical polishing drum in the direction of separation and contact;

Angle changing means for continuously or stepwise changing the angle at which the wafer comes into contact with the polishing cloth during polishing of the wafer outer peripheral chamfer;

Control means for controlling the advancing / retreating means so that the outer peripheral chamfered portion is pressed against the polishing cloth in accordance with or synchronized with the angle change of the angle changing means.ゥ We propose a polishing machine for the outer peripheral chamfer.

In the present invention, the angle changing means is not particularly limited. Any mechanism that can change the angle can be used. In other words, the wafer holding device is at right angles to the axis of rotation of the cylindrical polishing drum (rotary drum), with the axis parallel to the main surface of the wafer as the center, and at an arbitrary setting angular speed and in an arbitrary setting range. What is necessary is just to provide a mechanism that can swing and quantitatively change the reciprocating angle. At this time, the angular velocity does not need to be constant during polishing and can be arbitrarily changed, and the change may be continuous or stepwise. Continuous refers to changing an angular range (for example, 0 ° to 55 °) continuously and at a constant or different angular speed in a fixed cycle. Stepwise skips multiple angles. Polishing while changing the angle (for example, 45 degrees, 50 degrees, 55 degrees) while stopping.

The operation of the invention will be described.

The main cause of the variation in the polishing allowance of conventional polishing machines with a fixed angle is that different pressing forces are applied to each part. Therefore, in the present invention, by changing the angle of contact between the polishing pad and the polishing pad during polishing, the pressure applied to the outer peripheral portion of the wafer is equalized, and the variation in the polishing amount is reduced.

At this time, the relative distance of the outer peripheral portion of the wafer and the cylindrical polishing drum in the detaching direction changes due to the change of the angle of the wafer. An advancing / retreating means is required for the aerial holding device and the cylindrical polishing drum to relatively advance and retreat in the separating direction so that they come into contact with each other under pressure.

Such an advancing / retracting means is provided by an elastic force or mass biasing means such as a panel or a weight device, a air cylinder, a hydraulic cylinder, etc. This can be achieved by fluid pressing means by fluid pressure, mechanical movement means having a step screw driven by a pawl screw, or the like.

The control means extracts the change detection signal obtained from the drive source of the angle changing means (for example, step motor, servo motor, fluid motor) that changes the angle of the actuator from the encoder or pressure gauge, and calculates the amount of change in the detected signal. What is necessary is just to control an advance / retreat means based on it. Conventionally, in the wafer polishing machine of the outer peripheral chamfering type, in which the wafer is pressed against a cylindrical polishing drum in the form of a cylindrical polishing drum using a polishing cloth, the contact angle between the wafer W and the polishing cloth is adjusted before polishing. There was a tilting mechanism that did, but nothing changed during polishing. Also, there was no mechanism for controlling the relative position between the holding device and the cylindrical polishing drum synchronized with the change in the angle.

According to the present invention, the wafer angle held by the wafer holding device can be changed during the polishing, and the wafer can be polished while the chamfering position of the wafer W is changed by the angle change.

In the conventional wafer chamfering portion polishing, there is a chamfering polishing method of a similar mechanism using a tape having fixed abrasive particles carried on the surface. Since chamfering using these tapes can supply the tape continuously, there was no problem in the reduction of the polishing ability due to the deterioration of the polished surface. However, in the case of a cylindrical polishing drum using a polishing cloth, if polishing is continued in the same place, the polishing performance deteriorates quickly and the problem of the life of the polishing cloth comes out. This can be dealt with by raising and lowering the cylindrical polishing drum, but in the present invention, by polishing while changing the processing angle in step 18, the position in contact with the polishing cloth naturally shifts, and the life of the polishing cloth is improved. I do.

Regarding the improvement of the polishing cloth life, there is also a technique of pressing the peripheral portion of the wafer 18 on a flat polishing cloth and polishing using a wide range of polishing cloth area. However, using a flat polishing cloth was a problem because it took a long time to make it mirror-finished. In this regard, a method in which a polishing cloth is attached to a cylindrical polishing drum that can rotate at a high speed is preferable because the polishing ability is improved.

That is, if the polishing is performed by the cylindrical polishing drum in the present invention, the processing time can be reduced. Also, by changing the relative contact angle of the wafer W held by the wafer holding device with respect to the cylindrical polishing cloth, the contact position on the polishing cloth side is changed widely, thereby improving the life of the polishing cloth and improving the productivity. Can be. In addition, by changing the contact angle between the wafer W and the polishing cloth continuously or stepwise during polishing, it is possible to perform processing capable of controlling the variation in the polishing allowance. That is, the technique of changing the angle (changing the processing position) as in the present invention with a polishing apparatus in which a polishing cloth is attached to such a cylindrical polishing drum is particularly effective.

According to the present invention, it is possible to make adjustments such as changing the angular velocity of the angle change in a certain portion or temporarily stopping it by the effect of the chamfered shape, the previous process, and the like, based on the results of the trial. As a result, the polishing rate at each part can be made uniform, or It has become possible to make the polishing allowance uniform and the surface quality uniform by polishing by selectively polishing the surface. The polishing conditions, such as how much the contact angle between the wafer A and the polishing cloth should be changed, and at what angular speed it should be changed, depend on the above-mentioned prior application technology “Processing capacity of wafer outer peripheral portion”. Using the “evaluation method”, the polishing performance may be adjusted and set appropriately while checking the polishing performance. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a conceptual diagram of a conventional polishing apparatus for a chamfered portion of a peripheral portion of a belt.

FIG. 2 is a conceptual diagram (side view) showing an example of a polishing apparatus for an outer peripheral chamfered portion of a wafer [Example 1] of the present invention.

FIG. 3 is a conceptual diagram (plan view) showing an example of a polishing apparatus for a wafer outer peripheral chamfered portion [Example 1] of the present invention.

FIG. 4 is a conceptual diagram of an apparatus for simultaneously polishing the outer peripheral chamfers on the front side and the back side.

FIG. 5 is an explanatory diagram of a polishing rate evaluation method and evaluation points. (A) is an enlarged cross-sectional view of the chamfer on the main surface side of the A-A-Hachi, and (b) is an overall view of the A-A-H-A.

FIG. 6 is a table showing the measurement results of the polishing rates in Comparative Examples and Examples.

FIG. 7 is a view showing an example of the angle changing means 11 [Embodiment 2], and FIG. 7 (a) shows a state in which the wafer holding means is held vertically (the wafer is horizontal) on the cylindrical polishing drum. (B) is a diagram showing a state where the angle is changed. BEST MODE FOR CARRYING OUT THE INVENTION

Next, embodiments of the present invention will be described with reference to actual examples. However, the dimensions, materials, shapes, and other relative arrangements of the components described in this embodiment are not merely intended to limit the scope of the present invention, but are merely described, unless otherwise specified. It is only an example. Comparative Example 1, Comparative Example 2

Conventional mirror chamfering device, that is, polishing cloth 21a on the cylindrical surface as shown in Fig. 1 A cylindrical polishing drum (rotary drum) 21 with the affixed thereto, and a wafer holding device 20 that fixes the outer chamfer at a fixed angle while rotating the wafer W 20 The outer peripheral portion of the wafer was mirror-polished by using.

The pressure for pressing the wafer W and the polishing pad 21 a was applied with a weight of 2 kg attached to the wafer holding device 22 at a load of 2 kg. Polishing was performed by rotating the cylindrical polishing drum 21 one revolution at 800 rpm and the wafer W one revolution in 90 seconds.

The angle at which the wafer W is pressed against the cylindrical polishing drum 21 is set at an angle of 45 degrees by tilting the housing 22 forward about the support shaft 23 (see FIG. 2; (Comparative Example 1) and fixed at an angle of 55 degrees (Comparative Example 2), and the main surface side of Polishing was performed on the chamfered portion (so that the entire area of @@) was polished on the unexposed side, that is, on the front side. Example 1

2 and 3 show an example of the device of the present invention. The cylindrical polishing drum (rotating drum) 1 to which the polishing cloth 1a is attached is rotated at a high speed by a motor (not shown) built in or provided in the pedestal 17. These are mounted on a pedestal 17, and the pedestal 17 has an air cylinder 13 connected to a driving source including a compressed air supply means (not shown) and wheels 18 rotated by a driving force transmitted by the air cylinder. With this, advancing / retreating means 45 for moving horizontally on the surface plate 40 and in the direction of the arrow which is separated from the machining position of the chamfered portion is formed. The polishing drum 1 can move back and forth in the direction of moving away from the 18 W processing position. The wafer W to be polished is held by a rotatable wafer holding member 2 such as, for example, a vacuum chuck in a wafer holding device 25, and is provided in an intermediate mount 4 (not shown). It is rotated by a step motor. The amount of rotation is detected by a rotary encoder (not shown) provided in the intermediate gantry 4, and the detection signal is sent to a control circuit (not shown) provided in the intermediate gantry 4 and fed back as a control signal to the step motor to rotate. Control. Since such a configuration is publicly known, a detailed description is omitted.

In addition, the wafer holding device 25 has a holding angle of wafer A during polishing, that is, ゥ It is provided with angle changing means 11 that can change the angle of the chamfering position on the outer circumference of A-8. In other words, the e-holding member of the e-holding device 25 is rotatably mounted on the intermediate mount 4, but the intermediate mount 4 can swing about the support shaft 5 by a predetermined angle with respect to the main upper mount 16a. Is supported in a proper state. More specifically, the rotation angle becomes larger with respect to the position on the opposite side of the cylindrical polishing drum 1 from the wafer holding center, that is, the contact surface with the cylindrical polishing drum 1, in other words, the swinging arc becomes larger and the smaller angle It is rotatably supported on the gantry 16a by a support shaft 5 provided at a position where the processing position changes due to the change. Therefore, the wafer holding member 2, that is, the wafer W main surface, can change the angle with respect to the rotation axis of the cylindrical polishing drum with the support shaft 5 as the axis.

Next, the angle changing means 11 will be described.

中間 The rotation (angle change) of the intermediate mount 4 having the holding device 2 with the support shaft 5 as an axis is rotated by the step motor 9 so that the pole screw 6 is rotated. The angle of the female screw 7 to be screwed and the intermediate mount 4 are changed, and the link 8 connecting the fixed shafts is moved linearly, and the link 8 attached to the female screw 7 is used by the rotational moment given to the intermediate mount 4 . Reference numeral 10 denotes a rotary encoder, which is a rotation amount detecting means for controlling the speed and direction of rotation (angle change) of the wafer holding device.

Further, between the main lower frame 16 b installed below the main upper frame 16 a, there is interposed a reciprocating means 46 for moving the main frame 16 forward and backward in a direction away from the processing position of the wafer W. ing. That is, an air cylinder 13 connected to a driving source including a compressed air supply means (not shown) and a wheel 18 rotated by a driving force transmitted by the air cylinder 13 form a polishing drum 1 into the eight-chamfered portion. An advancing / retreating means 46 for moving in a direction of an arrow moving away from the polishing drum 1 is formed.

A fluid pressure for controlling the advance / retreat means 45 and 46 so that the outer peripheral chamfered portion of the wafer is pressed against the polishing cloth in accordance with or synchronously with the angle change of the angle changing means 11. In the control circuit, the control circuit 44 is a detection signal of an encoder for detecting the rotation of the step mode 9 which is the driving source of the angle changing means 11 for changing the angle of the wafer W. The fluid pressure of the air cylinders 13 and 14 is controlled in accordance with the amount of change of the signal.

Using such an apparatus, while supplying an abrasive of an alkaline solution containing colloidal silica from an abrasive supply nozzle (not shown) to the wafer W and the contact point of the polishing cylindrical polishing drum, a predetermined time of 18 W Was polished.

The pressure of pressing the wafer W and the polishing cloth 1 a is controlled by the weight (not shown) attached to the wafer holder 2 and the control of the cylinders 13 and 14.

The test was performed under a load of 2 kg. Polishing was performed by rotating the cylindrical polishing drum one revolution at 800 rpm and the wafer W at 30 seconds.

Also, by controlling the step mode 9 of the angle changing means 11 during machining, the angle 0 (see Fig. 2) is changed stepwise to 45, 50, and 55 degrees. At 0, the wafer W was rotated once (total polishing time was 90 seconds as in the comparative example), and the same region as in the comparative example was polished.

At this time, if the angle 0 at which the wafer W contacts the polishing cloth 1a changes, the wafer W may not be in contact with the cylindrical polishing drum, or on the contrary, an excessive force may be applied. Therefore, the fluid pressure of the air cylinders 13 and 14 is controlled based on the control circuit 44 to follow or synchronize with the angle change of the angle changing means 11 and the holding device 25 and the cylindrical polishing drum 1 Change the relative position of. The relative change between the wafer holding device 25 and the cylindrical polishing drum 1 is based on the pedestal 16, the air cylinders 13, 14 attached to the pedestal 1 及び and the wheels 18, 19. Adjusted at 6, 45.

For Comparative Example 1, Comparative Example 2, and Example 1, the polishing performance, that is, the polishing rate, and the variation at each part were confirmed. The results are shown in FIG.

The measurement of the polishing allowance and the polishing rate in each part of the peripheral area of JP 18 is disclosed in

The test was carried out according to the method described in No. 37 1655. That is, as shown in Fig. 5, a uniform film of polysilicon was coated on the surface of a mirror-polished wafer W having a diameter of 200 mm, and before and after polishing, the polysilicon film of each part was scanned with a scanning electron microscope. The thickness was measured and compared. The film thickness of the polysilicon before polishing was X, the film thickness of the polysilicon after polishing was Y, and the polishing allowance = XY. The polishing rate was determined by the polishing time. The chamfer shape is Although various types can be considered, the wafer A used in the present example and the comparative example was evaluated as a wafer W having a shape having a constant angle of inclination as shown in FIG. The measurement points are as follows: (1) the chamfer side near the boundary between the main surface and the chamfer (取 in Fig. 5 (a)), the inclined part of the chamfer (② in Fig. 5 (a)), and The measurement was taken at the outermost part (part ③ in Fig. 5 (a)). In addition, the evaluation was made at a total of six points including an orientation flat part on the outer peripheral part of the wafer and a position rotated 90 ° from the part.

As can be seen from the results, in Comparative Examples 1 and 2 performed by the conventional fixing method, it is understood that the polishing ability also varies considerably from part to part. On the other hand, in Example 1 according to the present invention, the variation of each part was improved. Example 2

Another embodiment of the angle changing means 11 is shown in FIG. Fig. 7 (a) shows the state where the wafer holding device is held vertically (the wafer W is horizontal) on the cylindrical polishing drum, and Fig. 7 (b) shows the state where the angle is changed. It is. The angle changing means 30 will be described in further detail. This is based on the support shaft 35 of the intermediate base 3 4 having the holding device 32, and the piston rod 36 is expanded and contracted by the air cylinder 39. This is a mechanism performed by a rotational moment applied to the intermediate mount 34 by the link member 38 attached to the piston rod 36. Even with such a mechanism, mirror polishing similar to that of the first embodiment can be performed. In other words, by moving the piston rod 38 of the air cylinder 39 of the angle changing means 30 during machining, the polishing can be continuously changed at an arbitrary angle range and at an arbitrary cycle, and polishing can be performed. It can be changed stepwise as in the first embodiment, and the same mirror polishing can be performed.

Note that the present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and any structure having substantially the same configuration as the technical idea described in the claims of the present invention and having the same effect can be obtained. It is included in the technical scope of the invention.

For example, in the comparative examples and examples of the present invention, a force is shown in which the chamfered portion (取, 1, ③) on one principal surface side of the wafer is polished. Polish not only the side but also the back side. To do this, first grind the surface side, Thereafter, the wafer W may be removed from the holding device, turned upside down and attached to the holding device 25, and then the polishing may be performed in two stages of polishing the back surface side. Alternatively, as shown in FIG. The cylindrical polishing drums 51, 51 with the cloth adhered are arranged at 180 ° symmetrical positions with respect to the wafer holding device 25, and the outer peripheral part of the wafer W and the outer peripheral part of the back face are simultaneously contacted. However, it is also possible to change the angle by the angle changing means for polishing.

The angle changing means may be constituted by a step motor or a rack-and-gear. In this embodiment, a fine tooth gear driven by a step motor or the like between the fixed main frame 16 'and the intermediate frame 42 is used. Means) 41, the rotation angle of the fine gear 41 is detected by an encoder (not shown) through the rotation angle of the step gear, and the detection signal is transmitted to the control circuit 44 to transmit the cylindrical polishing drum. The fluid pressure of the air cylinders 14 and 51 is controlled to follow or synchronize with the angle change of the angle changing means 11 so that the outer peripheral chamfered portion of the polishing pad presses against the polishing cloth. The advance / retreat means 45 and 46 are controlled so as to be in contact with each other. In such a two-sided arrangement method, since processing can be performed only by adsorption (holding) on one side, there is an advantage that processing can be performed without damaging the surface on which the device is formed. In addition, the angle changing means 11 may be changed within a range in which the entire front and back surfaces of the outer periphery of the ゥ A8 can be processed. However, in the device shown in Fig. 4 or the device that adjusts the angle so that the entire front and back surfaces of the wafer W can be machined, the relative positional relationship between the holding device and the cylindrical polishing drum is limited. It becomes complicated and it is necessary to consider the dimensions and arrangement of each part.

In addition, since the contact angle between the outer periphery of the wafer and the polishing cloth can be easily changed during polishing, processing can be performed according to the chamfered shape, for example, a round shape, an inclined shape at a certain angle, and other shapes. However, the shape of the chamfer on the outer peripheral portion is not particularly limited. Industrial applicability

According to the present invention, in the polishing of the outer peripheral portion of the device A, it is possible to make the polishing rate uniform at each part and to achieve uniformity of the polishing amount, and to achieve the in-plane distribution of the polishing rate, in other words, the polishing within a certain period of time. The variation in quantity was improved. The life of the polishing cloth was also improved by changing the angle and shifting the contact area of the polishing cloth.

Claims

The scope of the claims

1. While rotating the cylindrical polishing drum and the wafer with the polishing cloth adhered to the cylindrical peripheral surface, the outer periphery of the wafer is pressed against the polishing cloth, and the polishing cloth is rubbed against the outer peripheral chamfer of the wafer. In the method of polishing the outer chamfer of the wafer while

During polishing, the angle at which the wafer comes into contact with the polishing cloth is changed continuously or stepwise, and the outer peripheral chamfered portion of the wafer comes into pressure contact with the polishing cloth following or synchronizing with the change in the angle. The wafer outer peripheral chamfering method is characterized in that the wafer outer peripheral chamfering portion is polished by relatively moving the wafer 18 and the cylindrical polishing drum relatively in the direction of separation and contact.

2. While rotating the cylindrical polishing drum and the wafer 18 having the polishing cloth adhered to the cylindrical peripheral surface together, press the outer periphery of the wafer against the polishing cloth so that the polishing cloth is In a wafer outer chamfer polishing apparatus having a mechanism for polishing the outer peripheral chamfer while rubbing the chamfer,

Advancing and retreating means for relatively moving the cylindrical outer peripheral chamfered portion and the cylindrical polishing drum forward and backward in a separating direction;

Angle changing means for continuously or stepwise changing the angle at which the BA is in contact with the polishing cloth during the polishing of the outer peripheral chamfer,

Control means for controlling the advancing / retreating means so as to follow or synchronize with the angle change of the angle changing means, so that the chamfered portion of the outer peripheral surface of the wafer comes into contact with the polishing cloth in a pressurized manner. Wafer peripheral chamfer polishing machine.